Newsgroups: comp.os.ms-windows.misc
Path: cantaloupe.srv.cs.cmu.edu!crabapple.srv.cs.cmu.edu!bb3.andrew.cmu.edu!news.sei.cmu.edu!cis.ohio-state.edu!zaphod.mps.ohio-state.edu!uwm.edu!msuinfo!uchinews!att-out!cbfsb!cbnewsg.cb.att.com!rnichols
From: rnichols@cbnewsg.cb.att.com (robert.k.nichols)
Subject: Re: Permanaent Swap File with DOS 6.0 dbldisk
Message-ID: <1993Apr15.223142.9665@cbfsb.cb.att.com>
Summary: PageOverCommit=factor
Sender: news@cbfsb.cb.att.com
Organization: AT&T
References: <1qi0hc$an0@bsdns.brooks.af.mil> <93059@hydra.gatech.EDU>
Date: Thu, 15 Apr 1993 22:31:42 GMT
Lines: 50

In article <93059@hydra.gatech.EDU> gt4356c@prism.gatech.EDU (James Dean Barwick) writes:
...
>more on permenent swap files...
>
>i'm sure everyone who has an uncompressed part of their compressed hard disk
>has seen the message "you have selected a swap file greater than the suggested
>size...windows will only use the size suggested...do you wan't to create this
>swap file anyway" or something like that.
>
>well, a friend of mine (ROBERT) called microsoft and asked them what and why.
>what they said is that windows checks the amount of free disk space and
>divides that number by 2.  Then it checks for the largest contiguous block
>of free disk space.  Windows then suggests the smaller of the two numbers.
>
>They also said that under absolutely no circumstances...NONE!...will windows
>uses a swap file larger than the suggested size.  Well...that's what he 
>said!
>
>I call bull@#$#.  If this is true why does windows report the memory is
>available to me if it's not going to use it?

I think the support droid was malfunctioning and confused the disk space
limit with the virtual address space limit.  As far as the disk is
concerned, you are limited only by the amount of contiguous free space.
The limit that causes the message, "Windows will only use ...," is the
amount of virtual address space that the Virtual Memory Manager will
create, and this is a function of the amount of free memory that you have
when Windows starts.

In the [386enh] section of SYSTEM.INI, you can specify a parameter:

	PageOverCommit=multiplier

The following description is from the Windows Resource Kit:

	This entry specifies the multiplier what determines the amount of
	linear address space the VMM will create for the system, which is
	computed by rounding up the amount of available physical memory to
	the nearest 4 MB and then multiplying that value by the value
	specified for PageOverCommit=.  Increasing this value increases the
	amount of available linear address space, causing the size of data
	structures to increase.  This also increases paging activity
	proportionately and can slow down the system.  You can specify a
	value between 1 and 20.  The default is 4.  To change this entry,
	you must edit SYSTEM.INI.

--
Bob Nichols
AT&T Bell Laboratories
rnichols@ihlpm.ih.att.com
